Effect

Generation I

Roar can be used to automatically end wild Pokémon battles. It has normal priority, unlike in later generations. Even if a wild Pokémon uses the move, the battle will end. However, it has no effect in a Trainer battle.

Generation II

Now, when in battle against a Trainer, Roar will force a switch with a randomly chosen Pokémon from the Trainer's party. If there isn't another Pokémon, Roar will fail. It also has a priority of -1. If two Pokémon use Roar at the same time, the faster one will fail and the slower one will switch it out. Otherwise, it is the same as in Generation I.

Generation III and IV

Roar will fail when used against Pokémon with the Abilities Soundproof and Suction Cups or rooted by Ingrain. In Generation III, Roar has a priority of -5, which was decreased to -6 in Generation IV. If two Pokémon use Roar at the same time, instead of the faster one failing, the faster one will go first and switch the slower one out. Otherwise, it is exactly the same as Generation II.

Generation V

Roar no longer works on same- and higher-level targets in wild Pokémon battles, but can still force higher-leveled opponents to switch in Trainer battles, and can now be reflected with Magic Coat and Magic Bounce.

Exploud yells loudly and light blue circles come out of its mouth and at the opponent, causing it to become scared and run away. Sometimes, before it uses the attack, a flash of light blue light appears inside of Exploud's mouth.

Lillipup's body becomes outlined in a crimson aura and it yells loudly, releasing invisible shock waves from its mouth that expand outward. The yell has enough force to almost blow the opponent away. The opponent then goes back into its Poké Ball.

Herdier's body becomes outlined in red energy and it howls loudly, releasing invisible circles from its mouth that expand outward. The howl has enough force to almost blow away the opponent. The opponent then goes into its Poké Ball.